We propose to study the psychological and behavioral consequences of HTLV-III antibody testing using a longitudinal design in two separate cohorts. The San Francisco cohort is comprised of 683 gay and bisexual men recruited in November 1983 and May 1984 in a longitudinal study of the impact of AIDS on the sexual behavior of gay men. This group has been surveyed at six month intervals since May 1984. The Testing Center Cohort comprises 1200 persons recruited from the Alternative Testing Centers (established by law for HTLV-III antibody testing in California) in Alameda County (across the bay from San Francisco). This cohort will consist of male homosexuals, bisexuals, and heterosexuals, and female bisexuals and heterosexuals. Intravenous drug users will also be included in the study. The San Francisco cohort will continue to be surveyed at six month intervals, while the Testing Center Cohort will be surveyed before and after antibody test results, and at 1, 6 and 12 months following antibody testing. We will examine effects of antibody testing on a variety of variables including AIDS knowledge, anxiety, perceptions of susceptibility to developing AIDS, self-efficacy, and intentions to change and actual changes in sexual behavior and drug use. We will also examine the effects of health education at the testing centers on these variables, and if short and long-term social help-seeking activities are influenced by anxiety, self-esteem, and financial resources. We will also describe help-seeking behavior in these cohorts, the social consequences of positive and negative antibody status, differences between test-takers and non test-takers in the above variables, and differences between different sexual and drug risk groups on the above variables. Variables chosen for study were theoretically derived which integrates the Health Belief Model, Self-Efficacy Theory, and anxiety. Data from the proposed investigations will help identify variables which best predict psychological reactions and risk behaviors, suggest needed directions for preventive campaigns, and provide tests of current social-psychological models in a context of high ecological validity.